Fang Posted February 2, 2010 Report Share Posted February 2, 2010 (edited) Having a problem with a couple small gel cells for a fish finder and after switching to a small transformer charger they are now back up to 100% and holding a charge Gelled Electrolyte: Gelled batteries, or "Gel Cells" contain acid that has been "gelled" by the addition of Silica Gel, turning the acid into a solid mass that looks like hard Jell-O. The advantage of these batteries is that it is impossible to spill acid even if they are broken - the disadvantage is that they must be charged at a slower rate (C/20) to prevent excess gas from damaging the cells. They cannot be fast charged on a conventional automotive charger or they may be permanently damaged. This is not usually a problem with solar electric systems, but if an auxiliary generator or inverter bulk charger is used, current must be limited to the manufacturers specifications. Most better inverters commonly used in solar electric systems can be set to limit charging current to the batteries. Edited February 2, 2010 by Fang Link to comment Share on other sites More sharing options...
SlowPoke Posted February 2, 2010 Report Share Posted February 2, 2010 Thanks Fang, good to know. I was going to set up a 'charging center' in my shop for various items including the sonar battery; I'll just use the charger it came with instead of what I had planned. Link to comment Share on other sites More sharing options...
Sinker Posted February 2, 2010 Report Share Posted February 2, 2010 I've been charging the same 12V 7aH gell cell for 5 seasons now with my deep cycle battery charger on the 2A setting. No probs, battery still works mint. S. Link to comment Share on other sites More sharing options...
skeeter Posted February 2, 2010 Report Share Posted February 2, 2010 sinker you are right. i was going to post the same reply . 1 of the 4 that i have is on charge right now 2 AMP ONLY they are GREAT batteries and they last a long time before needind to be charged we use them for the lights in the hut,fish finder, 12V coffee mugs in the hut,......... 1 battery lasts all weekend. i just made up a 12v fan for the hut to blow the heat back down onto the floor . i also use one in my ski-doo for the electric start and it works great !!!!!!!!!!!!!!!!!! way cheaper then a new battery for it and just as good..... Link to comment Share on other sites More sharing options...
Terry Posted February 2, 2010 Report Share Posted February 2, 2010 2 amps should be fine 1.5 is better but as long as your battery doesn't get too hot you are fine heat is your enemy Link to comment Share on other sites More sharing options...
irishfield Posted February 2, 2010 Report Share Posted February 2, 2010 I have two 8ah batteries in my finder case. I use the 1000ma charger, for my 10 million candle power flashlight. Works like a charm ! Link to comment Share on other sites More sharing options...
Roy Posted February 2, 2010 Report Share Posted February 2, 2010 Here's another tip for those of you who have home/business security systems. Most backup power for those systems are 12V, 7.5 AH gels. Just buy one extra battery and keep switching them from the security system to whatever else you're using them for. Home security systems are almost all using a 1.5AH transformer so the battery from the system is always good. That's all I used when I had portable sonars and such. I've been using the same battery (ies) for 21 years. Link to comment Share on other sites More sharing options...
irishfield Posted February 2, 2010 Report Share Posted February 2, 2010 And it's good for them too Roy.. because the stay full charged in the alarm or back up light systems. Without them cycling they get pooched and using them in your finder is good for them. Link to comment Share on other sites More sharing options...
boatman Posted February 3, 2010 Report Share Posted February 3, 2010 (edited) Ideally you don't charge any deep cycle battery at greater than 10% of its capacity. In this case, 700mA. However, at work we used 2A chargers for years on the same 7.5A batteries with no ill effects - so guess what I use? Edited February 3, 2010 by boatman Link to comment Share on other sites More sharing options...
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